The present invention relates to a method of inspecting a process for manufacturing a semiconductor device, and a method of manufacturing a semiconductor device using this inspection method. More particularly, the present invention relates to a method of inspecting whether a semiconductor workpiece, which has been subjected to CMP (Chemical Mechanical Polishing), RIE (Reactive Ion Etching), etc., in the process for manufacturing a semiconductor device, is properly processed, and to a method of manufacturing a semiconductor device, in which after the endpoint of a current manufacturing step is detected by using this inspection method, the next manufacturing step is performed.
Recently, the width of wirings in semiconductor devices has become miniaturized. Furthermore, there are semiconductor devices that have a multi-layered wiring structure. Under such circumstances, the CMP (Chemical Mechanical Polishing) technique for smoothing semiconductor workpieces, the RIE (Reactive Ion Etching) technique, which is one of the anisotropic etching techniques, etc., are important techniques. Conventionally, inspection of a semiconductor workpiece, which has been subjected to the CMP, the RIE, etc., is performed in various ways, such as 1) inspecting the surface of a processed semiconductor workpiece with the naked eye by the use of an optical microscope, etc., 2) performing computer-analysis of the results of the measurement of a processed semiconductor workpiece, 3) measuring the thickness of each layer of a part of the surface of a processed semiconductor workpiece, and determining the condition of the entire semiconductor workpiece based on the measurement results, 4) calculating the average of the intensity of light reflected from the surface of a semiconductor workpiece, thereby determining the condition of the entire semiconductor workpiece.
However, it is extremely difficult to determine the condition of the entire semiconductor workpiece by simply measuring the thickness of a part of a layer of the semiconductor workpiece. Furthermore, it is difficult to inspect whether the minuscule wiring section is properly processed based on the above-described layer-thickness measuring methods. Moreover, the above-described layer-thickness measuring methods are performed based on, for example, the ratio of light reflected from the surface of the semiconductor workpiece. In such a case, it is necessary to analyze the reflectance, but an accurate measurement of the reflectance is required to perform the analysis. On the other hand, in the above-described methods for determining the conditions of the surface of a semiconductor workpiece based on the average of the intensity of reflected light, although it is possible to measure a vast area using these methods, all the information obtained for the measured vast area is not fully utilized. Accordingly, the inspection results are not very reliable. Furthermore, generally speaking, it is desirable if the time required for inspecting a semiconductor workpiece in each process step is relatively short.
A method of inspecting a process for manufacturing a semiconductor device, used to determine the status of a processing operation during the manufacturing process, according to an embodiment of the present invention, comprises: detecting an image of a desired area of a surface of a semiconductor workpiece after it has been subjected to the processing operation, using an image signal detector; detecting image signal intensity at each pixel of a plurality of pixels of the image signal detector; and determining the status of the processing operation based on the relationship between the image signal intensity and the number of pixels at certain levels of the image signal intensity.
A method of manufacturing a semiconductor device, according to the other embodiment of the present invention, comprises: performing either a polishing operation or an etching operation on a semiconductor workpiece; detecting an image of a desired area of the semiconductor workpiece after it has been subjected to the polishing operation or the etching operation, using a image signal detector; detecting image signal intensity at each pixel of a plurality of pixels of the image signal detector; and detecting an endpoint of the polishing operation or the etching operation by determining the status of the polishing operation or the etching operation based on the relationship between the image signal intensity and the number of pixels at certain levels of the image signal intensity, and proceeding to a next processing operation after the detection of the endpoint.